Explosive-bolt-activated spring-loaded actuation device

ABSTRACT

A pin pulling device moves a member such as a pin or shaft by a non-pyrotechnic actuation force, such as a spring(s). The actuation member or spring(s) is (are) held in the compressed and loaded position by a release mechanism, such as an explosive bolt coupled to the member through a retainer. When activated by a signal, the release mechanism is severed from the retainer and the member is actuated by the force of the actuation member or compressed springs as the springs expand.

This invention was made with Government support under contract no.F08626-95-C-0106 awarded by the U.S. Department of Defense. TheGovernment has certain rights to this invention.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is related to an actuation device. Moreparticularly, the present invention is related to an explosive activatedspring actuated device.

2. State of the Art

In the discussion of the state of the art that follows, reference ismade to certain structures and/or methods. However, the followingreferences should not be construed as an admission that these structuresand/or methods constitute prior art. Applicant expressly reserves theright to demonstrate that such structures and/or methods: do not qualifyas prior art against the present invention.

Certain actuation devices in use today, such as pin pullers, use apiston housed in a cylinder which is pressurized by a pyrotechniccharge. The pyrotechnic charge is detonated by an electrical current orother means. The resulting gas pressure forces the piston and anintegral pin or shaft associated with it to move over a predetermineddistance. The piston and pin or shaft are unique to the particulardevice application.

Conventional devices having the above-mentioned construction, and theirassociated methods, pose certain problems and disadvantages.

First, devices of the above-described construction are one-time use or“one-shot”devices.

Second, the use of the pyrotechnic force for activation and actuation ofthe device presents certain difficulties.

Use of the pyrotechnic charge for actuation results in ballistic shockimpact forces that must be taken into account in the design of thedevice. For instance, the housing and the pin of such devices must bedesigned with sufficient strength to withstand the forces created upondetonation of the pyrotechnic charge.

Also, since the explosive gas pressure created by the pyrotechnic chargedissipates immediately after actuation, a means of preventing“bounce-back” of the actuated pin is required. Typically, such devicesare provided with a mechanism for locking the pin in its actuatedposition. The requirement of providing such mechanisms furthercomplicates the design.

Moreover, choosing the proper size of the pyrotechnic charge is not asimple task. Generally, the charge must be large enough to effectivelyactuate the piston and its integral pin or shaft, but cannot be so largethat it causes problems such as excessive “bounce-back”, or fracture, ofthe pin.

The design of such devices is even more difficult when the pin or shaftto be actuated is relatively heavy. In attempting to design such adevice for actuation of a relatively heavy pin it has been found thatconventional practices for sizing the pyrotechnic charge and dealingwith the ballistics of the device are inadequate to lock the pin, andthereby prevent bounce back.

Thus, there is a need for an improved actuation device, and associatedmethod, which are both reliable and economical.

SUMMARY OF THE INVENTION

According to the present invention, device and method are provided whichovercome the disadvantages set forth above, and others.

According to one aspect, the present invention provides a pin pullerdevice comprising: a housing; a non-pyrotechnic actuation mechanismdisposed within the housing; a release mechanism constructed to initiatethe release of the actuation mechanism in response to an activationsignal; and a pin or shaft member operatively associated with theactuation mechanism.

According to a further aspect, the present invention provides a methodof actuating a pin or shaft, the method comprising: providing a housing;providing a non-pyrotechnic actuation device within the housing;providing a release mechanism; providing a pin or shaft operativelyassociated with the actuation mechanism; transmitting an activationsignal to the release mechanism; releasing the actuation mechanism; andactuating the pin or shaft.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

The objects and advantages of the invention will become apparent fromthe following detailed description of preferred embodiments thereof inconnection with the accompanying drawings in which like numeralsdesignate like elements and in which:

FIG. 1 is a perspective view of an embodiment of an actuation deviceaccording to the present invention; and

FIG. 2 is a longitudinal cross-sectional view of the device of FIG. 1.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

According to the present invention, a device, and its associated methodare provided in which a member to be actuated which is operativelyassociated with the device is actuated through separate release andactuation mechanisms. Preferably, the actuation mechanism is anon-pyrotechnic mechanism. By providing separate and distinct releaseand actuation mechanisms, the forces required for the release andactuation functions are separated, and thus become more manageablethereby facilitating design of the overall device. The terms “release oractivation” and “actuation” should be clear to those of ordinary skillin the art, particularly when taken in light of the description whichfollows.

Numerous configurations or devices, and their associated methods, arecomprehended by the concepts of the present invention. Specificembodiments of the present invention are described below, aided byreference to FIGS. 1 and 2.

FIGS. 1 and 2 illustrate a device 10 which is constructed consistentwith the principles of the present invention. The device 10 preferablyincludes a housing 15. The housing 15 can have any suitableconstruction. It is contemplated that the specific configuration of thehousing 15 can vary greatly, depending on the particular device and itsintended use or application. In the embodiment illustrated in FIGS. 1and 2, the housing 15 includes a base 20 having one or more throughholes 22 disposed therein, and a cooperating cover 25. A gasket member30 may be provided between the base and cover for the purpose ofproviding an appropriate seal. The material(s) from which the housing 15and its components are constructed depends upon the intended applicationor use of the device. For example, the housing 15 and its components canbe constructed of a stainless steel, which provides mechanical strengthand corrosion resistance. The gasket 30 can be constructed of anysuitable material, such as silicone rubber.

The device 10 further includes an actuation mechanism 35. Preferably,the actuation mechanism is non-pyrotechnic. Numerous mechanisms areenvisioned. One particularly suitable mechanism is a spring. The use ofsprings for the actuation mechanism 35 are beneficial in that the forcesgenerated by such springs are easily determined and/or modified therebyfacilitating design of the device 10. In the illustrated embodiment,actuation mechanism 35 is shown in the form of an arrangement ofbelleville springs or washers 37. The belleville springs 37 arebeneficial in that they are particularly compact thereby reducing thespace necessary for incorporating the actuation mechanism into thedevice 10.

A separate release or activation mechanism 40 is also provided in theillustrated device 10. In certain embodiments, the release or activationmechanism 40 is provided with a construction that it is responsive to anactuation signal. It is within the scope of the present invention thatthe release or activation mechanism 40 be constructed in a manner whichis responsive to one or more of any number of different types ofsignals. In certain embodiments, the release or activation mechanism 40is constructed to be responsive to an electrical signal. In theillustrated embodiment, the release or activation mechanism 40 is shownas an explosive bolt 42. The explosive bolt 42 is provided withelectrical connectors in the form of wires 45 for the purposes oftransmitting an activation signal. The explosive bolt 42 is furtherprovided with a scribe mark 47 which creates a weakness in the boltwhich fractures upon activation of the explosive bolt 42.

A member to be actuated 50 is further operatively associated with theoverall device 10, as well as the actuation mechanism 35. The particulartype of member to be actuated can vary considerably depending upon theintended use or application of the device 10. For example, the member 50can be constructed for reciprocating and/or rotating actuatingmovements, cutting, and/or the fracturing of frangible materials. In theillustrated embodiment, member 50 is in the form of a pin or shaft 52.

The above described components can be operatively arranged in anysuitable fashion. In the illustrated embodiment, the pin or shaft 52 andthe explosive bolt 42 are received within a respective through-hole 22formed in the base 20. One end of both the pin or shaft 52 and theexplosive bolt 42 are connected to a retainer member 55. The connectioncan be made by any suitable means. For example, the end of explosivebolt 42 may be threaded into a cooperating threaded blind hole formed inretainer 55, while the pin or shaft 52 is attached to retainer 55 via athreaded fastener or screw 60. A suitable number of belleville springs37 are received between the base 20 and the retainer 55. The particularnumber of belleville springs 37 utilized will depend primarily upon theforce necessary to actuate the pin or shaft 52, as well as the spacelimitations imposed on the device 10. In the illustrated embodiment,thirty-two such belleville springs 37 are utilized. The cover 25 is thenmounted to the base 20 with an intervening gasket 30.

The device of the present invention has a variety of applications inboth commercial and military mechanical systems. One specific example isthe incorporation of the device 10 of the present invention into thetail housing of an ordinance, with the pin or shaft 52 protruding into alocking mechanism in the control surface gearing (not shown). The wires45 of the explosive bolt 42 are connected to the control circuitry ofthe ordinance. The device 10 is mounted to the tail housing of theordinance by mounting screws (not shown) which are received within themounting holes 65.

An illustrative mode of operation is described as follows. An activationsignal, such as an electrical current, is carried through wires 45 andinto the explosive bolt 42. The explosive bolt 42 detonates and breaksin two, preferably along the scribe mark 47, thereby releasing thecompressed belleville springs 37 causing the retainer 55 and theattached pin or shaft 52 to travel backwards within the housing 15within the space defined between the retainer 55 and the cover 25. Inthe context of the specific control surface gearing applicationdiscussed above, the pin or shaft 52 would be withdrawn from the lockingmechanism of the gearing, thereby enabling activation of the controlsurface mechanism of the ordinance.

Among the advantages, of the present invention, particularly over apurely pyrotechnic design, is that the forces required to activate orrelease the member and the force required to actuate the member areindependent and thus more manageable. A spring can be sized for therequired load to pull the pin out of a control mechanism, and theexplosive bolt charge can be sized for breaking of the bolt. No lockingdevice at the end-of-stroke is necessary because residual spring forcesufficiently holds the pin in its actuated position, and little or nobounce-back occurs. Ballistic shock impact is eliminated with aresulting reduction in required strength of the pin and the housing.Also, fewer part types are used and the final production cost for thisunit is significantly less than conventional designs.

Although the present invention has been described in connection withpreferred embodiments thereof, it will be appreciated by those skilledin the art that additions, deletions, modifications, and substitutionsnot specifically described may be made without department from thespirit and scope of the invention as defined in the appended claims.

I claim:
 1. A pin puller device comprising: a housing; a non-pyrotechnicactuation mechanism having a longitudinal axis disposed within thehousing; a release mechanism comprising an explosive bolt having alongitudinal axis constructed to initiate the release of the actuationmechanism in response to an activation signal; the release mechanism andthe actuation mechanism being disposed in a relatively non-coaxialmanner; and a pin or shaft member operatively associated with theactuation mechanism.
 2. The device of claim 1, wherein the housingcomprises a base having a first through hole for receiving the releasemechanism and a second through hole for receiving the pin or shaftmember, and a cover.
 3. The device of claim 2, further comprising agasket disposed between the base and the cover.
 4. The device of claim1, further comprising a retainer disposed within the housing, theactuation mechanism and the release mechanism being connected to theretainer.
 5. The device of claim 4, wherein the pin or shaft isconnected to the retainer by a threaded fastener.
 6. The device of claim1, wherein the actuation mechanism comprises a spring.
 7. The device ofclaim 6, wherein the spring comprises a plurality of belleville springs.8. The device of claim 4, wherein the actuation mechanism is disposedbetween the retainer and a base.
 9. The device of claim 1, wherein thehousing comprises a base having a through hole, the device furthercomprising a retainer, and the release mechanism comprises an explosivebolt received within the through hole in the base and has an endreleaseably connected to the retainer.
 10. The device of claim 1,wherein the release mechanism comprises means for transmitting theactivation signal.
 11. The device of claim 10, wherein the means fortransmitting comprises wires, and the activation signal is an electricalsignal.
 12. A device comprising: a housing; a non-pyrotechnic actuationmechanism having a longitudinal axis disposed within the housing; arelease mechanism comprising an explosive bolt having a longitudinalaxis constructed to initiate the release of the actuation mechanism inresponse to an activation signal; the release mechanism and theactuation mechanism being disposed in a relatively non-coaxial manner;and a member to be actuated operatively associated with the actuationmechanism.
 13. The device of claim 12, wherein: the housing furthercomprises a base having a plurality of through holes and a cover coupledto the base; a retainer slidably disposed within the housing; theactuation mechanism disposed between the base and the retainer; therelease mechanism disposed within one of the through holes andreleasably connected to the retainer; and the member received within oneof the through holes and having an end fixed to the retainer.
 14. Thedevice of claim 13, wherein the actuation mechanism A comprises aspring.